#Pure Bash (no external utilities), 25

Based on @SophiaLechner's answer, this also prints a good number of ducks.

@OlivierDulac's idea to use the script shell PID as stored in the $ parameter saves 5 bytes.

echo "${$//?/duck
}"goose

Try it online.

Pure Bash (no external utilities), 25

Based on @SophiaLechner's answer, this also prints a good number of ducks.

@OlivierDulac's idea to use the script shell PID as stored in the $ parameter saves 5 bytes.

echo "${$//?/duck
}"goose

Try it online.

#Pure Bash (no external utilities), 30

Based on @SophiaLechner's answer, this also prints a good number of ducks:

echo "${RANDOM//?/duck
}"goose

Try it online.

#Pure Bash (no external utilities), 25

Based on @SophiaLechner's answer, this also prints a good number of ducks.

@OlivierDulac's idea to use the script shell PID as stored in the $ parameter saves 5 bytes.

echo "${$//?/duck
}"goose

Try it online.